It’s one of those “uh-oh” moments when you download a game over lunch break, say to yourself “I’ll give it a half-hour or so”, and then look up and see the clock flashing 3:46pm. Should I be surprised? Probably not — this is PopCap games, the maker of digital heroin since the early days of Bejeweled.

As a substitute for a Champions Online beta review, which isn’t going to happen today (alas), how about a glowing testimony of a great casual game that I am going to press on you like a pair of nice slacks?

At first glance, you might be tempted to say, “Another tower defense game?” when you see Plants vs. Zombies — resist that urge, however! It is of the devil! The tower defense genre has blanketed the casual gaming market like crazy over the past few years, everyone rushing to pump out the next Desktop Tower Defense yet never quite succeeding. However, I never realized how stale and predictible tower defense games had gotten until I booted up PvZ and witnessed how they took a familiar genre and refashioned it into something almost brand-new.

Instead of mazes where critters dutifully plod down a path between all of your nasty death-spewing towers, Plants vs. Zombies eschews mazes entirely in favor of… a lawn. The setup is that a horde of goofy, lovable zombies are marching on your house (from right to left), and if they get there, your brains are forfeit. In a cool twist, it isn’t humans and their awesome shotguns to the rescue, but… plants. For some reason known only to them, the plants surrounding your house are fiercely devoted to saving you from the zombie menace, up to and including sacrificing their own lives.

Juxtaposing plants against zombies, at first glance, is incredibly weird — like saying “orange juice vs. tractor trailors”. The two don’t have much to do with each other. Yet, against all odds, it works, and it works brilliantly, mostly because both sides feature huge amounts of personality and variety, and because plants make good stationary objects (towers) while everyone loves blasting zombies (critters) into oblivion.

The zombies appear in one of five rows (or lanes) as they march on your house, cheekily represented as lawn mower marks on the grass. Most of them are slow and plodding, but as you progress up through the levels you start facing more formidable challenges — football zombie (who’s super tough), a pole-vaulting zombie (who jumps over your first line of defense), a Michael Jackson-ish zombie (who calls backup zombie dancers to do “Thriller”) and more. Each round is composed by a steady stream of zombies, as well as a few points where a huge wave of the undead appear.

In your defense, as I said above, are plants. And not just any plants — by the time you finish the adventure portion of the game, there are about 40 different plants you can throw into combat, an obscene number for a tower defense game. The catch is, for each level you can only choose a set amount of plants to take with you (it starts at 6, but you can earn more slots). This introduces a rich layer of strategy — the game lets you peek at what type of zombies you’ll be facing that round, and you can construct your seed “deck” accordingly. This adds huge replayability, especially as you try out more creative combinations (one of my favorites so far is a burning treestump — torchwood — that turns any peas shot through it into fireballs). You also have one last line of defense, a lawnmower in each row that’s set to roll over the first zombie to reach the left part of the screen — but this can only be done once per row per level.

Since there aren’t any mazes, Plants vs. Zombies lets the zombies engage the plants directly, attacking and destroying them as they reach them. Because of the disposable nature of the plants, you aren’t spending gobs of time upgrading them as you are replacing them and reshaping the battlefield. Another change from traditional tower defense games is that the currency you use to plant plants — “sun” — isn’t earned by killing zombies, but by catching falling sun icons and planting sunflowers and other flora that produce this resource.

I spoke to its addictive nature, and I meant it. This is a game that sucks you in and makes you plead for “just one more round” as the world crashes down around your shoulders. I appreciate that the game’s creators occasionally interject unique levels that deviate from the normal setup, usually in the form of a minigame. For example, attacking zombies by “bowling” wall-nuts down the field (trying to bank the nuts to score multiple hits), playing whack-a-mole as zombies pop out of graves, or eschewing the sun resource altogether and using plants that roll down a conveyer belt to defend your house.

There are tons of unlocks, minigames and special modes to be had here, even when the main adventure is done (including a survival mode). I really can’t speak any more highly of Plants vs. Zombies — I went home, gave a copy to my wife, and watched her get sucked in as well (occasionally growling at naughty zombies who defied her wishes). It’s a perfect casual title, and one that will probably keep me occupied for quite some time to come.

I’m through 3/5 of the adventure levels. There is fun to be had by doing the mini-games for more cash for the shop: quad-cannon pea-shooters are super-fun and not that expensive (450 sun, payable in two easy installments).

That level 3-10 was an insane kind of easy fun. They give you triple-shooters, flaming stumps, walls, and a little more. My entire screen was a mass of flying, flaming peas, and zombies were dropping before they made it to the first square. Slight balance issue on that one, but fun.